Ampex 601 Manual
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Table
of
Contents
I.
DESCRIPTION
AND
SPECITICATIONS
GENERAL
SPECIFICATIONS
II.
PRINCIPLES
OF
OPERATION
THEORY
m.
INSTALLATION AND
OPERATION
GENERAL
POWER
LINE
INPUT
MICROP
HONE
INPUT
REPRODUCE
OUTPUT
INTERCONNECTING
CONNECTORS
STUDIO INSTALLATION
TAPE
THREADING
RECORDING
WITH
HALF
TRACK
MACHINES
REPRODUCING WITH
HALF
TRACK
MAClllNES
RECORDING
REPRODUCING
3r
d
EDITION
REWIND
AND
FAST
FORWARD
ERASING
MIXING
OCTOBER
1958
SYNTHETIC
REVERBERATI
ONS
IV
.
TAPE
TRANSPORT
ASSE
MBLY
GENERAL
ST
AIID-BY
OPERATION
PLAY
MODE
REWIND MODE
FAST
FORWARD MODE
ROUTINE
MAINTENANCE
V.
ELECTRONIC
ASSEMBLY
GENERAL
RECORD CHANNEL
REPRODUCE
CHANNEL
BIAS AND ERASE OSCJLLA
TOR
ELECTRONIC
ALIGNMENT
ALIGNMENT
AND
TEST
EQUIPMENT
REQUIREMENTS
VI,
PARTS
LIST
List
of
Illustrations
Fig.No,
Caption
FRONTlSPIECE
2-1
TAPE
MAGNETIZATION
2-2
RECORDING HEAD
2- 3
MAGNETIZATION
CURVE
2-4
OUTPUT
VS.
FREQUENCY
2-5
ACHIEVING
FLAT
RESPONSE
3-1
SPACE
REQUIREMENTS
3- 2
TAPE
THREADING AND
NOMENCLATURE
4-1
MECHANICAL
OPERATION
SIMPLITIED
4-2
ROUTINE LUBRICATION
4-3
TAPE
TENSION
MEASUREMENTS
4-4
TAPE
TRANSPORT
EXPLODED
VIEW
5-1
REPRODUCE
AMPLIFIER
RESPONSE
5-2
RECORD
AMPLIFIER
RESPONSE
5-3
SCHEMATIC DIAGRAM
~
1
-1
1-1
1- 2
2-1
2-1
3-1
3-1
3-1
3-1
3-1
3- 1
3-2
3-2
3-2
3-3
3-4
3-4
3-4
3-5
3-5
3-5
3-5
3-6
4-1
4-1
4-1
4-1
4-3
4-3
4-4
5-
1
5
-1
5-
1
5-1
5-
1
5-2
5-2
6-1
Page
2-1
2-2
2-3
2-4
2-5
3-2
3-3
4-2
4-3
4-5
5-4
5-7
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I.
Description &
Ss:,ecifications
The
AMPEX Model 601 is a
li
ghtweight, portable, magn
et
ic tape
recorder designed for prof
ess
ional use, and
is
available in any combina-
tion
of
these versions:
Power lnptJt
Tape
Speed
Head
Assembly
117 volts, 50
or
60
cycles
per
second (cps)
7!
'2
or
3¾
inches
per
seconds (ips)
fu
ll
or
half track
An accessory transformer (Catalog No. 173:
H-l)
featuring conven
ie
nt
,
quick plug-in change fr
om
high to low impedance microphone i
nput
is
ava
il
able for use wi
th
this mode
l.
The
machine can
be
operated in the
horizontal
or
vertical position. It is packaged in a durable, luggage-type,
saddle-tan Samsonite case,
or
is obtainable uncased for custom instal-
lation.
TABLE
1-1
EQUIPMENT
SUPPLIED
TAPE
SPEED
TRACK
LINE
FREQ
AMPEX
DIMENSIONS
UN
IT
!lPs)
WIDTH !CP8)
CAT.NO.
( I
ns.)
Complete
Equipme
nt
(l
n
carrying
7-1/2
t1a1r
60
7948-1
16-
l /
2xl
3-3/4x8.
Case)
7-1/2
Full
60
7948-2
16-1
/2
x13-3/4x8
.
7-1/2
Half
50
794
8-5
16-1
/
2xl
3-3/4x8.
7-1/2
Full
50
7948-6
16-l
/
2xl3-3
/
4x8
.
3-3/4
H
alf
60
7948-101
16-1/2xl3-3/4x8.
3-3/4
Full
60
7948-102
16- l /
2xl3-3/4x8
.
3-3/4
H
air
50
794
8-105
16-1/2xl3-3
/
4x8.
3-3/4
Fu
ll
50
7958-106
16-1/2x13-3/4x8.
Tape
Transport
7-
1
/2
Fial!
60
6200-14
9-5
/
16xl2-l
/2x5.
7-
1
/2
Full
60
6200-10
9-5/!6xl2-l/2x5.
7-1/2
Ralf
50
6200-15
9
-5/
16xl2-
l
/2x5.
7-1/2
Full
50
6200-11
9-5/16xl2-l/2x5.
3-3/4
H
air
60
6200-121
9-5/16x12-l/2x5.
3-3/4
Full
60
6200-122
9-5/16x
1
2-l/2x5.
3-3/4
Ralf
50
6200-123
9-5/
1
6x
l
2-l/2x5
.
3-3/4
Full
50
6200-124
9-5/16x
l
2-l
/2x5.
Electronic
7-1/2
17416- 1
6-1
/
8xl2-1
/
2x5.
Assembly
3-3/4
17416-101
6-1
/8xt
2-l
/2x
5.
Power
Cord
CS-5
96.
Mating
Connector,
Microphone
Input
PL-33P
Miniature
Phone
Plug,
Li
ne
Input
PL--450
Mating
Plug
,
Out
pi:.
PL-44
5
No
tes:
1.
A
ll
macing connectors are supplied without wiring as a convenience
for diversified installa
ci
on.
2.
Ha
rdware
ki
ts are
ava
il
able to facili
cai:e
maintenance. (See Sec-
GENERAL
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SPECIFICATIONS
1-2
Tape
Width
Reel Size
Tape Speed
Playing
Time
Reproduce
Timing
Acrnracy
Flntter and Wow
Starting
Tim
e
Stopping
Tim
e
Fast
Forward
Time
Rewind
Tim
e
Freq1f
ency Response
Si,?nal-10-Noise Ratio
R
eco
rd Inputs
Reproduce
Output
0 perating Contro/J
¼ inch.
7 inch,
RETMA
reel
(maximum).
7½ ips, tull track.
7½
ip
s, half track.
3¾ ip
s,
full rrack.
3¾ ips, half track.
Full
Tra
ck
-32
minutes with 7 inch reel,
7½ ips, 1
200
fee
r.
Half
Track-6/4
minutes wirh 7 inch reel,
7½ ips, I
200
feet.
±0.29?,
or
an accuracy
of
±}6
seconds
in
a 30-minute recording.
71/i
ips-Below 0.17% rms.
3¾
ips-Below 0.3% rms.
The
tape attains full speed
in
less than one-
fifth second
in
either the play
or
record mode.
less rhan one second.
90
seconds for full 1
200
foot reel.
90 seconds for full 1200 foor reel.
7½
ips-40
to 15,000 cps
±2
db
50 ru
10,000 cps down no more than 4
db
ar 15,000
cps.
3¾
ips
--±2
db
50 to 7500 cps.
Full
Tra
ck-ove
r
55
db
below peak r
ec-
ord level. Peak record level is defined
as
rhe
poinr
of
3ri: roral rms harmonic distortion
measured while using a
400
cps tone; and
peak record level includes bias, erase and re-
produce amplifier noise.
Half
Tr
ack-50
db
below peak record
lev
el.
MICROPHONE:
Accommodates any high
impedance microphone, and can be quickly
converted for a low
imp
edance microphone
with
rhe plug-in accessory transformer (Cat-
alog
No.
17331-1).
LJNE: 0.5 vole required for normal program
level.
l.23 voles rms into 600 ohms
at
program
level.
PLAY
-REC:
The
play mode is selected
by
placing rhe swirch in PLAY position.
Th
e record mode
ca
n be selected
only_
by de-
pre
ssing the safety button
at
the same rime
the selector switch is placed
in
REC
posirio
n.
Th
e safety button, a flat topped neon la
mp
,
remains
li
ghte
d while the machine is in the
record mode.
REWIND-FAST
FWD
:
This
selector
switch is mechanically
int
erlocked with the
PLAY-REC
switch.
Reproduce O1itput
Operating Controls
Miscellaneo:u
Monitoring
Head Assembly
Power Requirements
A
ccesso
ries
MIC REC LEVEL, and LINE REC LEVEL
SPEC
IFIC
AT
I
ONS
are separate mixing conrrols.
Th
e
MONITOR
SELECTOR switch is used
for monitoring
as
described in the following
paragraphs; but it functions also as an oper-
ating control. In the PLAY mode, rhe
MON-
ITOR selector switch must be in the
TAPE
position in order to bring the reproduce head
signal to the
OUTPUT.
A roggle
ON
-OFF switch, located on the
control panel, turns power on
or
off.
When
placed in rhe
ON
position, this toggle switch
will cause the capstan to rotate; bur the rape
will nor move unril one
of
the two operating
switches is mrned from its neutral position.
The
MI
CROPHO
NE
input, a t
hr
ee circuit
connector, is conve
ni
enrly located on rhe con-
trol panel.
The
PHONES
output
is
a two circuit jack,
located
on
th
e
fr
ont
panel.
The
LINE
INPUT
connector
is
a rwo
ci
rcuit
jack recessed into
tlhe
right side
of
the equip-
ment.
The
OUTPUT
connector is a three circuit
jack also recessed into the right side of the
equipment.
Mating connectors are supplied (see Table
1-1).
The
MONITOR
SELECTOR switch allows
monitoring
of
program input,
or
repr
oduce
output. A phone jack
and
illwninated v-u
meter are on the
front
panel.
When
the
TAPE
position is selected, the re-
produce
output
can be monitored.
Wh
en the INPU1[' position is selecred, the
headphones and merer report
pr
ogram signal
level.
Separate erase, record, and reproduce heads
are contained
in
a single housing.
117 volts, 50
or
60
cps; 0.52 ampere, 61
warts.
Maintenance
Kit
:
Speed Conversion Kits to:
3¾
ips,
60
cps
7½
ips,
60
cps
3¾
ips,
50
cps
71/i
ips,
50
cps
6392-1
7556-0
7556
-1
7556-2
7556-3
1-3
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SPECIFICATIONS A
cceJJo
ri
es
1-4
Conversion Kir
co:
50 cps operation, 7½ ips
60
cps operation, 7½ ips
50
cps operation, 3¾ ips
60
cps operation, 3-¾
ip
s
Adapror for rack
mounting
Spare parrs kits for:
7½ ips,
60
cps machine
7½ ips,
50
cps machine
3¾
ips,
60
cps machine
3¾ ips,
50
cps machine
Min
or hardware
Kir
s:
9738
9739
9740
974 I
9684-1
9742-l
9742-2
9742-3
9742-4
7802
See Section VI for a complete parrs list.
II. Principles of Operation
If a material capable
of
being magnetized
is
placed in
rh
e prox1
m1ry
of
a magnetic field, rhe molecules of rhe material will be
or
ie
nt
ed
according
to
the
direction of rhe
fi
eld. Any of several methods can be
used
co
produce the magnetic field,
bur
of
most inreresr in magnetic
recording
is
rhar field produced when a current
fl
ows through a coil of
wir
e.
The
current may be
der
ived from a
transducer-for
example, a
microphone converting audio sound waves ro electric current.
Magnetic recording tape consists of finely divided iron-oxide par-
ticles deposit
ed
upon
a plastic backing.
This
rape
is
moved through a
magnetic field in which
rh
e magn
et
izing force
is
alternating, and rhe
iron oxide particles are align
ed
according ro rhe instantaneous direction
and magnitude of
the
fi
eld (See Fig.
2-1).
TAP
E
s N s
FLUX
N s N
:=]
:=@
:~
s N s
/"\
S
IGNAL
----..--~-~
\J
.--------.-e
F
ig.
2-
1.
Tape Magnetization
Magn
etic
Tape
2-1
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Magn
eti
c
Head
Ma
gneti
za
ti
on
Curv
e
Bias
2-2
The
magnetic field
is
produced in
rh
e
gap
of a recording head,
over which the recording
tap
e passes.
Th
e recording head is a ring-
shaped electromagnet (See
Fi
g.
2-2).
Ir
consists of an incomplete ring
of highly permeable material inserted in a coil of wire.
The
discontin-
uity in
the
ring
forms
the
ga
p,
a
nd
the ring
is
rhe core of the electro-
magnet.
-
------
e
------~
""'
Fig. 2-2. Recording Head
The
magnetization curve of the i
ro
n ox
id
e utilized as the recording
medium is simil
ar
to that shown
as
the heavy line
in
Fig. 2-3. At points
near
the
origin, the c
ur
ve
is
extremely non-linear, and the signal record-
ed on the cape would n
oc
be directly proportional to the signal
app
li
ed
to
the
head.
Thi
s would result in a high degree of distortion upon re-
production.
This
distortion is greatly reduced by the application of a
hi
gh-frequency constant am
plitude
bias signal which is mixed with
the
signal being recorded.
Th
e frequen
cy
of this bias is genera
lly
selected
to be five ti.mes the
upp
er fre
qu
ency l
im
it
of
the recorder to
pr
.event
beating between the
bi
as and harmonics of rhe recorded signa
l.
While
the
tape is in
the
recording gap, the bias causes the magnet-
ization characte
ri
stics
of
the iron oxide to follow the dashed line loops
shown
in
Fi
g. 2-3, known as the
MlNOR
HYST
E
RE
SIS LOOPS. As
th
e t
ape
leaves the gap,
the
influence of the magnetic field created by
th
e
bi
as
is
reduced to zero, and
the
tape assumes a p
erma
nent magnet-
ization, known as
REMANEN
T
INDUCTION,
determined
by
the gap
flux
at
th
e time the tape leaves
the
ga
p.
After
the
recording process, there exists on
ch
e cape a flux paccero
which is proportional in magnicude and
di
rection to the signal recorded
on it. If
the
rape is then
mov
ed
past
the
gap
of
a reproduce
head-
which is similar in construction ro the record
hea<l-rhe
magnetic flux
of
th
e moving rape will induce a voltage in the coil
of
the
re
pr
oduce
B
(INDUCTION)
H
(
MAGNETIZ
I
NG
FORCE)
MAGNETIZATION
CURVE
CO
MPOSITE SIGNAL
AT RECORD
HE
AD
I
I
SATURATION
LEVEL
I I
1-1---
1 I
I I
I I
SIGNAL
Pig. 2-3. Magnetization Cttrve
head. This i
nduc
ed voltage is proportion
al
to
the
numb
er
of
cums
ot
wire on the head, and the rare of change
of
flux,
exp
ressed in the fol-
lowing equation:
E=N(d¢)tft)
Wher e E is
the
induc
ed
vo
lt
age
N
is
th
e
numb
er of
turns
of
wir
e
d~t
is
th
e
ra
te
of
chan
ge of
flux
It
is
desirable that
the
gap in the reproduce head be as small as
possible, so
that
the
gap will interce
pt
less than one wave
le
n
gth
of
the signal
on
the
tape
at
the highest freq
ue
ncy
to
be reproduced. How-
ever,
as
the
gap
is made smaller
the
induced voltage decreases, so there
is a practical limit in decreasing the gap and st
ill
maintaining an ade-
qu
at
e si
gna
l-to-noise ratio.
Induced
Voltag
e
in H
ead
2-3
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2-4
Induced
Voltogc
in
Head
The
voltage induced across the head 1s computed by
the
following
equation:
E =
Bm
V
sin
,,.%
Where
E
is
the
induced
voltage
B
is
the
maximum
flux
density
of
the
recording
material
V
is
the
velocity
of
the
tape
over
the
head
w
is
the
gap
width
~
is
the
wavelength
of
the
signal
on
the
tape.
From this expression
it
can be seen chat
the
voltage across the coil
increases directly as the velocity increases a
nd
as the wave-length de-
creases (frequen
cy
increa
ses).
If
th
e rape velocity and
ga
p width a
re
assumed
to
be consranc, the
output
voltage from
the
head
is
directly
pro
-
portional
to
the frequency, as long as the wave length on the rape is
l
arge
compared co
the
gap
width.
This
results ;n
an
output vs.
fr
e
quen
cy
charact
er
istic such as shown in c
ur
ve A of Fig. 2-4.
The
voltage does
not
continue
co
rise indefinite
ly
.
As
electrical losses in the core mate-
rial increase,
and
as the wave-length on the rape
ap
proa
ches the same
dimensions as
th
e
repr
oduce head gap, the actual
output
res
em
bl
es curve
B
of
Fig
. 2-4.
OUTPUT
r
(db)
, , r r r r :
I I I I I I I
+
25
_______
Jr--1--------Jr--j----
----
1--- ♦
-----1
I I I I A I : :
+20
________J
___
!--------1---~
--------
'
---t----
J
I I I I I I :
l : : I I I I
♦
15
-------
r---r--------r
__
J
______
Jr
-
--'-----
◄
I I I : I : I
+10
________J
___
!--------1---~-
~~
-
t----
-t----J
I I I I I
'ii
I
: I
!~
I I ' :
+5
--------r--.lr-------
-.\
______
__
J
___
_.,.
____
,
: :
,,__~
I : :, B l
o
--------
:---1-----,
oc,
--t
--------
+--
-r
---
-:
-5
--------
~
---~-
~
--~
__
j
_______
jr_J
____
_
~
I I
Co
I l I : :
-10
________J
___
J
_______
J
___
i--------!---~-----
1
: : : : : : :
-15
--------
i--
--------~
--J---
------~--~
-
--
--~
I I I : I I I
-20
--------
1
__
J
________
J
___
l-
--
-----
1
---
!
-----
!
I : : : : : :
-
25
------
--i---~--------~---'r
--------~--J
____
_
-4
: : : I I : :
I I I I
10
100
1000
IO
KC
FREQUENCY
Fig.
2-4.
Output
vs. Freqttency
In
order
to
provide an o,·erall frequency response
that
is
flat (see
Fig.
2-5)
an
equalization circuit consisting
of
a series
re
sistance and
capacitance
is
inse
rt
ed
in one
of
the early srages
of
the re
pr
oduce ampli-
fi
er.
This
equalizer has a high-frequency
droop
characteristic (curve B,
Fig.
2-5)
which is the inverse
of
the
rep
roduce
head
characc
er
iscic
(curve
A,
Fig.
2-5).
In
or
der
co
extend the high-frequen
cy
response,
additional equal
iz
ation
is
included in the record amplifier in the form
of
a high-frequency boost circuit,
de
signed
to
compensate for the
dr
oop
in reproduce head characteristics caused by head core losses,
gap
losses
and recording losses.
DECIB
ELS
________
_________________
T
____________
T
____
,
PLAYBACK'
! : : : :
•
25
--
EQUA
LI
ZAT
IO
N -----1---~-
PLAYBACK
~
CURVE ' j' HEAO :
+
20
-------
'
--+--
----
-+--,-C
HARACTERISTICS t
B I I I I I • I
♦
15
--------!--
1
--------l---~------
~i
o o
ro
O
__
J
: I : : 0 0 O : : :
♦
1
0
---------~--J
__ -----~--J
__
.!
___
_J
,--
4
--
---:
: ! : :
••
: ! :
+5
--
------1---
r-----
--1--.f-- OVERALL - -
--
-{
I I I
••
I RESPONSE :
o -----
--
.....,1
I
.._--,-4-
----•
, 1 C 1 0" 1 : 1 1
',
:
-5
-----
1
--l---!----
......
•
_J__
1
--------!---~---'
J
: :
••
: I : l :
-10
--------~--J,-_,l-----~--~--
----
-t--1-----~
I
1J'
I I I I I
-15
________J
__
,J
________
J
___
i-
----
1-
--~----J
I O I I I I
A, o0 I : I :
10
50
500
FREQUENCY
Fig. 2-5. Achieving Flat R
es
p
ome
IOKC
Frequ
enc
y Resp1onse
2-5
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Ill. Installation
and
Operation
This machine can be operated in either the horizontal
or
vertical
position. In the carrying case, insrallacion consists only
of
making up
and connecting the required cables (See "Connector" in chis secti
on).
For studio installations, an adaptor (Catal
og
No. 9684-1) is available
which permits mounting
in
a standard 19-inch relay rack.
The
power requirements are 117 volt a-c, 50 or 60 cps, 0.52 ampere,
6 l watts. A name place on the botrom
of
the case adjacent to the aper-
cure for
OUTPUT,
UNE
INPUT
and l l7
v.
a-c indicates rhe proper
line frequency.
The
1ine input
is
an unbalanced bridging input of l00,000 ohms.
Any unir connected to rhe LINE
INPUT
connecror should deliver a sig-
nal
of ar least 0.5 volr when recording from consolerres, mixers or other
rape recorders.
The
recorder is wired for a high impedance microphone,
but
pro-
vision for internal mounting of an accessory plug-in transformer imme-
diately changes the machine for use with low impedance microphones.
To
make rhis conversion, remove the four screws on rhe panel
of
rhe
electronics assemb
ly
.
The
panel and assembly can then
be
removed.
A.
High
Impedance-a
dummy
plug
Jl
07P
shown on the sche-
matic diagram (Fig. 5.3) must be plugged
int
o socket
Jl0
6S for hi
gh
impedance op-
eration.
B. Low Impedan
ce-
remove the dummy
plug
J107P. Acces-
sory transformer
AMPEX
catalog number
17331-1
(s
hown
as
Tl03
on
sch
emat
ic dia-
gram
Fig
. 5.3) is then plugged into }10
6S
for impedance in the range
of
150 ohms
co
250
ohms.
C. 30
ohm
to
50 ohm-Install transformer
Tl03
as shown
on
the
schematic diagram ( Fig. 5.3) by plug-
ging
the
transformer
into
socket ]106,and
removing che jumper as shown
in
Nore 7
on
th
e schematic.
The
output
of
rhe machine should be connected
co
a unit having 600
ohms
input
impedance. In a situation wherein the recorder will work
into a high
im
pedance line, physically terminate the
OUTPUT
connec-
tor wirh a
600
ohm resistor and bridge this resistor
with
rhe hi
gh
im-
pedance circuit. A three circuit
OUTPUT
plug is supplied. A cwo circuit
plug can
be
used, and will work;
but
it
automatica
ll
y makes an unbal-
anced line. If
an
AMPEX amplifier loudspeaker is used
plug
it into the
MONITOR
jack only.
GENERAL
POWER
LINE INPUT
MICROPHONE
INPUT
REPRODUCE
OUTPUT
3-1
www.SteamPoweredRadio.Com
INTERCONNECTING
Re
ga
rdless
of
application observe
the
re
quir
ements
und
er "Line
Input"
and "Reproduce
Output"
when
interconnec
ting
the
machine with
an
y
other piece
of
equipment.
3-2
CONNECTORS A power cable and marching plugs for the
MICROPHONE
(JI
01S
),
LINE
INPUT
(]10
2S),
and
OUTPUT
(JI
04S)
connectors
are
s
up
-
plied
with
the
equipment.
Shielded, low-capacity cable is re
comme
nded for
making
up
input
and
output
cables. Make such cables as shore as possible for intercon-
ne
c
ting
units in
audio
systems.
Refer
co
the
schematic diagram ( Fig.
5.3),
to
determin
e correct
pin
conn
ec
ti
on for all plugs.
STUDIO
The
reproduce head
cab
le is d
ou
ble shielded, insuring against r-f
INSTALLATION
pi
ckup. Cable capacity and length have been minimized
co
avo
id
high
frequency loss. In general, mo
unt
the
electro
ni
c assembly and cape trans-
port
no mo
re
than
o
ne
foot apart.
If
che r
epro
du
ce head cable is len
gt
h-
ened for gr
ea
ter separation of
the
components, high fre
qu
ency response
wi
ll
be
affected. In the
eve
nt an in
sta
llation absolutely d
ema
nds len
gth-
ening
thi
s cable, a very low capacity rype (
RG
-62/
U)
is
in
dicated, plus
the
addition
of
an
ourer shield.
Hi
gh fr
eq
uen
cy
losses cannot be ke
pt
co
a
minimum
if
the
cable l
ength
exceeds three feet.
Space requirements for custom installation
are
given in the accom-
panyin
g illu
st
rati
on ( Fig.
3-
1
).
All
ow
suffi
cient
clearance
at
the
right
side
of
the electronics chassis for easy access
to
LINE
INPUT
and
OUT
-
PUT
co
nn
ecto
rs.
If
desired, these conneccors can
be
brought
co
a parch
pane
l
mounted
at
some
more convenie
nt
point in
the
inscallacion ro
pr
o-
vide ready accessibility.
Fig.
3-
1. Space R
eq1
ti
rcments
Th
e cape threading
path
described bel
ow
is
the
same for all modes
of operation; but special attention is ca
ll
ed
to
the
notes dealing
with
half crack heads.
St
ep
1: Place a r
ee
l of cape on
the
left-hand
cu
rnrable, and iui
empty
ree
l
on
the
ri
gh
t-hand
turnt
able,
making
certain
tha
t
the
pins
around rhe base of each
sp
indle en
gage
cor
responding s
loe
s
on
the
reel
hub
s.
Step 2:
St
ep
3:
Press a reel hold-down
knob
in place on each spi
ndle
.
Thr
ead
the
cape as indicated in
th
e fro
nti
spiece.
Mak
e sure
the
ox
i
de
or dull surface is against
th
e heads.
Step
4:
Anchor
the
rape in rhe slot
on
the
em
pry r
ee
l
hub
if desired,
but
a
full
cape
turn
councerclockwise around che reel
hub
is
usua
ll
y sufficient.
HEAD
ASSEMBLY
REEL
MI
CROPHO
NE
MONITOR
LINE
MI
CROPHO
NE
RECORD
SELECTOR
RECORD
INPUT
LEVEL
LEYEL
CAPSTAN
IDLER
GUIDE
POST
CAPSTA
N
R
EWIND
FAST·FORWARD
CONTROL
Pl.AY-RECOAO
CO
N
TROL
RECORD
SAFETY
BUTTON
Fig.
3-2
.
Tap
e Threading
and
NomenclatNre
NOTE
Because machines using half track heads
record
or
reproduce only half
the
cape wi
dth,
the
t
ape
supp
ly
must
be
so
oriented chat
th
e
half
to
be
recorded is farthest from
th
e cape
transp
ort
surface.
After
the
e
ntir
e rape has
been wound onto che take
-up
reel from a re-
cording
run, for instance,
the
take-
up
r
ee
l
muse
be
turned over a
nd
the
second half re-
corded--or
indencifi
ed
for a lacer
run.
For
ex
ample:
TAPE THREADING
3-3
www.SteamPoweredRadio.Com
3.4
RECORDING
HALF TRACK
REPRODUCING
HALF TRACK
RECORDING
Step l:
Step 2:
Step 3:
Step
4:
Step 5:
Step 6:
Thread a tape
as
directed under "Tape Threading.''
Set rhe machine
as
indicated in "Recording," immediately fol-
lowing.
The
ent
ire tape must be reeled onto the take-up reel, regardless
of
whether
or
not the recording
is
completed. FAST
-F
WD
can be used if
pr
ogram material does not use the entire tape.
Rem
ove the rake-up reel from the machine and turn
it
over.
Remove the turntable reel which is now free of rape.
Place the take-up reel
on
the curntable side.
Reversing the take-up reel after a recording run, places the tape in the
only position for
pr
ope
r threading from the turntable s
id
e; and also
o
ri
ents the st
ill
unrecorded half of rhc tape so that it
is
farthest from the
cape transport.
If
the rape had been
re
wound, the second run would
have erased the previous recording.
Refer to the steps in "Re
pr
oduce," following.
The
half track rape will
reproduce correctly only if oriemed
so
that the half of the
ra
pe desi
reJ
is
farthest from the rape transport surface.
In reproduce mode, afcer the entire rape has been r
ee
led onro rhe take-up
re
e
l,
reverse rhe
re
el and
pl
ace ir on rhe rurnrable side.
Previous
ly
recorded capes are erased automati
ca
lly
as new recordings
are made, eliminating the need for an erasure run because the tapes
first pass over the erase head whenever the machine
is
recording; bur
for rhe finest recording, it
is
recommend
eJ
that the rapes be tank erased.
Step 1:
Step 2:
Step 3:
Step
4:
Connect the program source equipment (microphone, mixers,
etc.)
co
the
ap
propriate input.
P.la
ce the
MONITOR
SELECTOR switch on the
INPUT
function.
Place the
ON
-
OFF
toggle in the
ON
position.
Adjusr either the MIC REC LEVEL or the LINE REC LEVEL
concrol, depending
on
whether rhe
MICROPHONE
input
or
the LINE
INPUT
is
being
us
ed, so th
at
on the most incense
volume peaks of the program
to
be recorded, the v-u meter
ne
edle swings to approximately zero on the v-u scale.
It
is
unnecessary
co
scare
the cape morion in order
co
sec
the pro-
gram leve
l.
lf only one input
is
being used, turn
che
oc
her
REC LEVEL to zero.
Step
5:
Place rhe PLAY-REC control in the REC position
by
de
pr
ess-
ing the safety bucron ar the same rime rhe record position
is
selected.
Th
e transparent plastic button glows while rhe ma-
chine is in the record mode. This record safety fea
tur
e prevents
accidental erasure
of
previously recorded rapes.
Wh
en return-
ing
to the PLAY
or
rhe neutral position at rhe dot, the safety
butron
is
not used.
While
recording, a continuous comparison of the incoming program
and
ch
e reproduction on the
cap
e
ca
n be effected
by
mrning the
MON
I-
TOR
SELECTOR switch back and forth between
rh
e
INPUT
and
TAPE
positio
ns
and observing the v-u merer, or using headphones.
To
srop recording, return the PLAY-REC control ro neutral, marked
by a dot.
Step 1:
Step 2:
Step 3:
Step
4:
Step 5:
Thread a previously recorded cape on the machine.
Place the
ON
-OFF roggle in the
ON
position.
Place
the
PLAY-REC control in the PLAY position.
Place the
MONITOR
SELECTOR switch in the
TAPE
posi-
tion.
Adjust the reproduce level through the volume control
of
the
program source.
If there is no
output
, check the
MONITOR
SELECTOR
switch position.
When
the machine
is
in the play mode,
the
MONITOR
SELECTOR switch muse be in the
TAPE
positio
n.
OUTPUT
can be monirored wirh the head
ph
on
es
plugged into the jack on the front pane
l.
To
rewind or move tape forward rapidly, place
REWIND-
FAST
FWD
switch in the position desired.
The
tape moves
at
800 feet per
minute in either direction, and can be shuttled back and forth between
REWIND
and FAST
FWD
positions without waiting for the cape
co
decelerate
or
srop.
Th
us, cueing and editing
ca
n be accomplished
ac
high speed with no danger
of
tape breakage.
Th
e
REWIND
-FAST
FWD
and
PLAY-REC
controls are mechani-
cally interlocked, making impossible the switching
of
either control
unless the other
is
in neutral.
This
safety feature guards against cape
breakage which would occur if the machine were switched directly from
either
of
the high speed modes ro PLAY or REC positio
n.
CAUTION
Always return
REWIND-FA
ST
FWD
control
co
neutral
position, and wait
tii
tape motion stops before switching to
PLAY
or
REC. Placing
se
lecror controls
on
PLAY
or
REC
while
tap
e
is
in motion will cause stretched or broken tape.
To
erase a previously recorded cape when no new reproduction
is
de-
sired,
turn
both
of
the R
EC
LEVEL controls
ro
zero and run the tape
in the record mode.
Because microphone and line recording channels are independent, each
governed by its own level control, sim
ul
taneous recording from rwo
sources can be made with
out
an external mixer.
For example, singing, voice announcements
or
inscrumencal accom-
paniment
ca
n be dubbed into a program being recorded from a con-
solette
or
other tape recorder.
To
effect chis, connect the program source
equipment co the LINE
INPUT
conneccor and a microphone
co
the
MICRO
PHONE
connecror. Adjust both the
MICROPHONE
REC
LEVEL and LINE REC LEVEL controls for desired balance between
the two programs.
RECORDING
REPRODUCING
RE
WIN
D ANCI
FA
ST
FORWARD
ERASE
MIXI
NG
3.
5
www.SteamPoweredRadio.Com
3-6
SYNTHETIC
REVERBERATION
Special effects, similar to those obtained through the use of
an
echo
chamber can
be
created easily.
Connect a microphone and set the program level as usual; then connect
the
OUTPUT
conneccor
co
the
LINE
lNPUT
conneccor,
turn
the
MONITOR
SELECTOR switch
co
TAPE, and
scare
recording.
The
re-
verberation decay race, which
is
the time required for the echo
co
die
away, can be varied with
che
UNE
REC LEVEL control.
The
Control
value chosen
wiU
depend entire
ly
on
the effect desired.
If
the control
i.s
sec
coo
high, continuous oscillation will result, and the v-u meter needle
will swing to maximum and remain there.
If
this happens, adjust ro a
lower setting.
IV. Tape Transport Assembly
The
cape transport mechanism incorporates a single-speed synchronous
mocor and a system
of
pulleys, belts, and clutches
co
drive the capstan
and the turntables. Three modes
of
tape mocion (PLAY,
REWIND,
and FAST
FORWARD)
are determined by two controls located
on
the cop panel
of
the tape transport.
(The
n
eut
ral position for each con-
trol
is
marked by a doc.)
The
bracketed numbers in this section refer to pares shown in Fig. 4-1,
Fig. 4-4, and in the parts list
at
the end
of
this manual. For greatest
facility in following the discussion below, it is suggested that Fig. 4-4
be opened fully for ready reference.
Power
is
applied to the drivemotor (
63)
when the
POWER
switch
on
the front panel
of
the electronic assembly
is
turned to the
ON
position.
The
capstan (
42)
begins
co
rotate imn~ediacely, being driven
by
a
nyl
on belt (
68)
which runs between the motor pulley (61) and rhe
capstan flywheel. A second belt (
69)
running in a groove in the cap-
scan flywheel drives the play takeup pulley (
40).
The
shock relief
brake rollers (
2)
are engaged against the rubber-tired fast forward and
rewind clutches (16 and
31).
Both rurntables are motionless, a
nd
che
machine
is
in standby
co
ndition.
Since the capstan
is
in mocion when the machine is in the standby con-
dition, the tape will acceler
ate
to full play speed almost instantly when
the PLAY switch
is
operated, thus producing a wow-free scan.
When
the PLAY control
is
energized the following mechanical se-
quence occurs:
1)
The
play takeup pulley (
40)
and belt (
69)
are brought
co
bear
on
the play takeup clutch
(19).
2)
The
shock relief brake roller (
2)
on the play takcup side
is
re-
leased from the fast forward clutch tire (
16).
3)
The
capstan idler (
79)
engages the capstan (
42),
which drives
the cape, pulling it from the tape supp
ly
turntable (i.e. the rewind
turntable) and feeding it
co
che
takeup turntable, which now be-
gins
co
rotate. It
is
especially important
co
understand that when
the machine
is
operating normally
in
the play mode, in which the
cape
is
clamped against the capstan by the capstan idler, the turn-
tables are effective
ly
isolated from each other.
The
takeup turn-
table, as its name implies, does nothing more than cake
up
the tape
fed to
it
by rhe capstan. It does nor pull the tape from rhe rape
supply turntable.
4)
The
shock relief brake roller (
2)
on
the rewind side remains en-
gaged against the rewind clutch tire (
31),
and slippage occurs
between the clutch and disc assembly (
30)
.
The
friction produced
in this slippage, and
che
friction produced by the rewind holdback
brake
(37)
operating
on
the bakelite
drum
(35)
provide the re-
quired holdback tension.
GENERAL
STANDBY
OPERATION
PLAY
MODE
4-1
www.SteamPoweredRadio.Com
REWIND
TAKE
UP
0 SHOCK RELIEF BRAKE
@)
HOLDBACK
BRAKE
0 REWIND IDLER e
PLAY
TAl<EUP
PULLEY
@
FAST
FORWARD CLUTCH @ C
APSTAN
FLY
WHE
EL
e
PLAY
TAKEUP
CLUTCH e
MOTOR
PULLEY
@)
HOLOBACK BRAKE
@)
NYLON
DRIVE
BE
LT
(0
REWIND
CLU
TCH
@
TAKEUP
BELT
@ HOLDBACK BRAKE
ORUM
@
CAPSTA
N
IDLER
Fig.
4-1.
Mechanical Operation Simplified
4-2
The
REWIND-FAST
FORWARD
control cannot
be
operated unless
rhe PLAY control
is
in
neutral.
When
th
e
REW
I
ND-FAST
FOR-
WARD
control
is
turned
co
REWIND:
I )
Both
shock relief brake rollers (
2)
are released.
2)
The
rewind idler (
7)
is
clamped between
the
mocor pulley (
61
/
and
the
rew
ind clutch
tire
( 3l )
and
the
rewind
turntable
is
driven.
3)
Holdback tension is provided by
the
holdback brake (
25)
on
the
rakeup assembly as tape
is
pulled from
the
cakeup turntable.
When
the
REWIND-FAST
FORWARD
control
is
turned
co
FAST-
FORWARD:
1)
B
oth
shock relief brake rollers (
2)
are
released.
2)
The
rubber-tired fast forward clutch (
16)
is
brought
co
bear
on
the
moror pulley (
61)
and
drives the cakeup
turntab
l
e.
3)
Holdback tension is produced by
the
holdback brake
(37)
on
the
r
ewind
assembly.
N
OTE
5
OIL
HC
A[
N0TCS
l 6
'l
4 fllCCO
MM
CNOEO
LU8
R
1C
ANT
5
CAL
OIL
OC,
TUR
9lN
[ •
11.
OR
8Ulf'C:A£5T
.t,
i! FOUR QA
FIVE
0FIOP5
or
OtL
l
"-$
M
UGi.
OIL
AS
T~C
8EAAING
W
ILL
A
CCEPT
WIPf.
A
WA
Y
f:ICCESS
00
N
OT
SATUAAlE
Fhl
WASI-CCR
TO
OIL
THIS
ftE•AING
~
CXACll'f
rouR
0R0PS
Fig. 4-2. R
outine
L1tbrica1ion
REWI
ND
MODE
FAST
FORWARD
MODE
4-3
www.SteamPoweredRadio.Com
4
-4
ROUTINE
MAINTENANCE
Cleaning
Lubricati
on
Routine maintenance
of
the
cape transport mechanism consists pri-
marily
of
periodic cleaning and lubrication.
Cleanliness
of
all
parts
of
the tape drive mechanism
is
required
for
con-
sistent
optimum
performance. Mose tape manufacturers lubricate the
ir
tapes; chis lubricant will gradually form a coating
on
the head assembly
and
the
idler wheels
and
may cause loss
of
positive drive at the capstan.
Therefore, periodic cleaning
of
both the head assembly and
al
l
parts
of
the
tape drive mechanism
is
particularly important.
The
recommended
agent
for cleaning
Ampex
Head
Assemblies is a mixture
of
Xylene
and
0.1% Aerosol.
This
agent
is available in 2
oz.
bottles.
(Ampex
Catalog
No.
FP-7.)
To
clean any head assembly simply wind a clean, lintless
cloth on a swab-stick
and
moisten with chis mixture. Swab
the
heads
periodically
to
remove all dirr and oxide which may have accumulated
f~om
the
tape. Clean all pares except the head assembly with a clean,
lmtless cloth moistened with denatured alcohol.
CAUTION
Do
noc
use any ocher solv
ents
as there are some which may damage the
adhesive used
to
hold the head laminations together.
The
recommended standard lubricant for the four places which re-
quire periodic lubrication
(motor
and capstan)
is
Caloil
No
. OC-11.
This
lubricant is available from
AMPEX
as Stock
No.
T0-9
( ½ oz.
oiler)
or
FP-5
(4 oz.)
NOTE
The
proper
lubricant is available from
AMPEX
as Stock
No.
T0
-9
(
Vi
oz.
oiler)
or
FP
-5
(4
oz.).
The
upper
and l
ower
bearings
of
the drive mocor should be lubricated
after every
500
h
ours
of
operation.
The
upper
oil hole
of
the motor
is
accessible through a hole in the tape transport
gri
ll
e slighcly above
and
to
the
left
of
the takeup turntable. For access to the lower oil hole, lo-
cated in the side
of
rhe moror end bell, remove rhe tape transport from
the case (See Fig.
4-2).
Four
or
five drops
of
one
of
the recommended lubricants is sufficient.
Care should be taken
to
avoid over-oiling
or
sp
ill
s.
Any such excess
should
be
wiped away
with
solvent.
The
capstan may require oiling
about
once for every four oilings
of
rhe
drive motor.
For
access
co
the
upper
bearing, the capstan idler muse
first
be
removed (See Fig.
4-2)
. Remove the rubber cap
on
the idler.
Remove the hairpin retainer
and
lift
the
idler off its shaft, caking care
not
to
lose the washers associated
with
ir.
The
aluminum
plug-boccom
over the capstan shaft may
now
be pried off and the felt washer beneath
it
removed
co
expose the
upper
capstan bearing.
Use
as
much
of
one
of
the
recommended lubricants as the bearing will accept,
wipe
away
any excess,
and
reassemble.
CAUTION
Do
not
oil
the
felt washer which serves only as a dust protector
and
to
keep
oil from working its way
up
the capstan.
For access
to
the
lower bearing,remove the tape transport from the case.
The
oil hole
is
located in the bearing housi
ng
as shown in Fig. 4-2.
Ure exactly fottr drop1
of
oil
--
no
more.
Do
not
o
il
any ocher
parts
of
the
tape
transport mechanism. All
other
bearings and moving pares are lubricated for life.
le may be said
in
ge
neral, chat most of the difficulcies char will normally
be
encou
nt
ered
in
the
Model 601 tape transport mecha
ni
sm will
be
traceable
to
contamination
of
belcs, pulleys, bearings, a
nd
ocher friction
surfaces,
whether
due
to
carelessness in routine lubrication,
or
to
rhe
gradua
l accumulation of d
irt
a
nd
other foreign
ma
terial
to
be
expected
over a reasonable l
ength
of time. Correction
of
these difficulties will
usually be a macrer
of
careful disassembly and cleaning, rather
than
re-
adjustment of
the
mechanism.
Th
e normal torques (and hence, rape
tensi
on)
in
this mechanism are,
in
fact, fixed within strict design speci-
fi
cations, and are noc adjustabl
e.
The
measurement
of
these
to
rques will
frequently provide a
rap
id means for isolati
ng
the source
of
mechanical
troubles.
~
~
~
,,...
_ I
3/4
OZ
-IN
,
2-3
112
OZ~IN
. T
AKE
U"'
s-~
1
111
.
HOLNACK
114
-~ • l
fl
.
NO
TES
HOLOBACK
3/ 4 - •
,,.
oz-
1N
TAK[U"'
5- 7
oz.-1N
,
I.
IF
ftEEl
HUB
DIAMETER
IS
•. AAOER Oft SMALLEIIII
THAM
2 UICHIES,
111-
ULTlflLY
SPl'tl
N
(J
!SCALE
lltEAO\frtO ev
HUS
ftADIUS
TO
O
BTA
IN oz.- ,.
JtfAD
INI .
2:
P'UlL
SCALE: W
ITH
STEADY
MOTION WHEN
MEA
SUftl
NG
HO\.DIACK
T!NSIGJU'
.
ALLO
W
SCALE
TO
MOVE
IN TOWARD
REEL
WH
E N M
EAS~.umu•
TAICIEUI' T
IJitSION.S
.
TAKE A
LL
READINGS
WHI
LE
SC
A
LE
IS
IN
M
OTION.
Fig.
4-3. Tape Tension Measurements
Mecha
nical
Troubleshooting
4-5
www.SteamPoweredRadio.Com
4-6
Torques
and
Tape Tension
Takeup
Tension
H
oldba
ck Tension
Malfunct
i
on
s
in
Pl
ay
Mod
e
The
measurement
of
rorques
on
the
Model 601 requires the following
equipmenc:
I ) A light-movement
spring
scale (e.g. Post-A-L
et,
0
to
8 oz., Exact
Weight
Scale Co., Columbus, Ohio.
2)
A
measuring
hub.
A standard
RETMA
plastic
re
el
may
be used. If
the
hub
diameter
is
exactly 2 inches,
the
spri
ng
scale will read
directly
io
ounce-inches. Reels
with
smaller
hubs
can
be
brought
up
to
2-
inch
diameter
by
winding
on
sufficient tape. If a reel
of
greater
than
2-inch
hub
diameter
is used, multiply
the
spring
scale
reading
by
the
hub
raditts
to
obtain
the
ounce-inch reading.
3)
A piece
of
string,
approximately 30 inches long, with a small loop
tied
at
one
end.
Torques
measured
on
the
driven
turntable
in any mode, (
i.e.
the
turn-
table
on
which
the
tape
is
being
wound)
are
a measure
of
ttikrmp ten-
sion.
Torques
measured on rhe
turntable
from which the rape
is
pulled
in any mode
are
a measure
of
holdback tension (See Fig.
4-3).
Step I:
Step 2:
Step 3:
Pla
ce
the
measuring
huh
on
the
driven turntable.
Wind
a f
ew
turns
of
string
around
the
hub
in
the
direction
of
normal
tape
wrap,
and
attach
the
spring
scale ro
the
loop
ar
the end.
Scarr th1
e machine in the
appropriate
mode
and, as
the
string
,is wound
on
the
hub
, allow
the
SG,le
ro move in
with
it, tak-
,,
ing
the reading while the scale
is
in morion.
Normal
torques
are as follows:
Fa
st
Forward 5
ro
7 oz-in.
R
ew
ind 5 ro 7 oz-m.
Play 2
to
3½
oz-in.
Step
1:
Place rhe measuring
hub
on
the
turntable
from which rhe
tape
is
pulled
in
the
mode
in operation.
Step
2:
Wind
rhe sering on fully in rhe direction of normal rape wrap,
and
attach
the
spring
scale.
Step 3: Stare
the
machine
in the
oppropriate
mode, and pull
the
scale
slowly in rhe d irecrion in which rape
is
norm
ally pulled from
this reel, raking rhe r
eading
while
rhe scale
is
in steady mo-
tion.
Normal
torques are as fo
ll
ows:
Fasr Forward ¾ ro l ¼ oz-in.
Rewind
¾ ro I¼ oz-i
n.
Play
5¾
tO
8¾
oz-in.
These values listed above for borh
rakeup
and
holdback tensions may
be
close to the low
er
limit when rhe machine
is
new, and will usually
move
up
toward rhe
upper
limit aftt:r tht: first
10
or
12
hours
of
opera-
tion.
Nearly
all malfuncrions in rhe play
mode
will be reflected as flucrer and
wow in excess of spt:cifications. A quick check
of
rakeup
and
holdback
tensions, discussed in rhc previous section, may lead directly
to
the
source
of
trouble. Possible causes
of
Aurrer
and
wow are suggested in
the following check list.
The
word "contaminated," as used here,
may
indicate
either
rhe pres-
ence
of
oil where it is
not
wanted,
or
accumulations
of
dirt
and
other
foreign
matter
on
pulleys
and
belr. In
either
cast,
carbon tetrachloride
i:s
recommended as rhe cleaning agent.
After
cleaning-a contaminated
part,
clean any
othe
r
part
with
which ir normally comes
imo
contacr
vvherher
or
not
that
part
shows any
immediate
evidence
of
conrami
na
-
tion. Bracketed
numbers
refer
ro
parts
shown in the explodc<l view
of
the
mechanical assembly, Fig. 4-4, which should serve as a
guide
for
a.ny
necessary
dis<l,-~sembly
and
reassembly.
R
ewind
and
fast forward malfunctions will usually
be
reAecred as an
a.pparent loss of
power
in rhose modes, loose cape
wind,
e
rr
atic rape mo-
rion
or
slippage, a
nd
, possibly
no
rewind
or
fast forward ar al
l.
The first
seep is
to
make a quick check of
rewind
or
fast forward cakeup and
holdback tensions as described previously.
The
malfunctions discussed
below
apply
ro
eirher
mode,
the
turntables, associated components, and
rape direcrions
being
opposite
of
each orher.
Scarring,
sropping,
and
shuttling
malfunctions will be evidenced by
the
throwing
of
rape loops and, in
extreme
cases, by rape breakage.
Thes
e
troubles
are
usually associated wirh low
rakeup
tension of brake mal-
functions produced
primarily
by
tampering
or misassembly, or conram-
ination
due
co
careless o
iling
or
accumulati
on
of
dirt.
The
following section covers some ad
justment
s,
cr
itical clearances,
and
a.lignment which muse be
maintained
in reassembling parrs of rhe rape
transport
mechanism
that
may have been disassembled for servicing.
Two
general precautions should
be
observed in any
requir
ed disassembly:
1.)
Always
note
rhe
number,
type,
and
location
of
washers
in
an
as-
sembly
very carefully. Should washers,
retainers
or
ocher smaU
hard-
ware
be
lost
or
damaged
in
servicing, a
kir
containing
an
assortment
of
such
hardware
(Ampex
Catalog
No.
7802)
is available
through
your
dealer.
2)
To
·remove
the
sub-place-(
1),
a preliminary ro any further disas-
sembly
of
pares
under
the
cop place casting, remove only
the
three
elastic scop-nurs
that
hold
it
,
and
clevis
pin
chat links
the
slide lever
( I
3)
co
the
lower yoke
of
the
rewind
/fast forward acruaror (
48).
le
is unnecessary
co
remove
the
adjustment
screws (
70
and
71)
for
the
capstan
thrust
and
the
mocor rhrusc.
lf
the
settings
of
these
screws
are
changed, they
must
be
carefully readjusted as described
in
the following subsections.
The
thrust
discs (
65)
beneath these
screws,
being
coated
with
grease, will usually sray in place
when
the
sub-plate is removed. It
is
advisable,
how
ever,
co
be
sure char
they
do
not
fall out.
Ir
will generally be found easiest
co
re-install
the
sub-place
after
servicing, if rhe
PLAY
conrrol
is
energized.
The
cape transport incorporates
rubber
shock
mounts
on
the
screws
re
-
taining
rhe
motor
mounting
place
co
the cop
plat
e casting.
The
se
shock
mounts
provide
automatic
centering
of
rhe
drivemotor
and
no
adjust-
ments
are
necessary.
lrhe drivemoror
thrust
is
a hardened steel ball (
60)
against a nylon
Malfunctbns
in P
lay
Mode
Malfuncti
o
ns
in
Rewind
or F
ast
Forward
M
od
e
St
ar
ting
,
Sto
pp
ing
a
nd
Sh
ut
tling
Malf
unctions
Assembly
and
Construction
Notes
Dr
i
vemotor
Thrust
4-7
www.SteamPoweredRadio.Com
Drivemotor Thrust
Turntable Height
Play Takeup Clutch
4-
8
disc (
65).
The
capstan
thrust
is
adjusted by a set-screw (
70).
End
play
of
.010
in.
to
.015 in.
is
required,
and
is
obtained
as follows:
Step I: Coar
the
nylon
thrust
disc liberally wirh wheel
bearing
grease
and
drop
it
through
the
threaded
ho
le in
the
sub-place (
1)
over the capstan shaft.
Step 2: I
nsert
the
sec-screw,
and
tighten
down
unti
l
it
is felt
co
bot-
tom
on
the
thrust
disc.
Step
3:
Grasp the capstan flywh
ee
l (
42)
between rhe
thumb
and
in-
dex
finger.
Step
4:
While
maintaining
a sl
ight
downward
pressure
on
the
head
of
the
set-screw
with
the
screwdriver (
to
simulate
the
pressure
th
at
will l
ater
be applied by rhe loc
king
screw)
stare backi
ng
the
screw off slowly,
and
work
the
capstan flywheel
up
and
down
unt
il
an
audible click
at
the
ends
of
its travel indicates
the presen
ce
of
end
play.
This
will usually occur
when
the
set-
screw has been backed off
approximately
¼
of
a turn.
At
this
po
i
nt
, e
nd
play should
be
in
the
required range.
Step
5:
Tighte
n
the
locking
nut
on che ser scr
ew,
then
re
check
end
play.
Turntable
height
(
the
distance measured from che
top
surface
of
the
turntab
le (
78)
to
the
perforace<l metal
grille)
should
be
.125 in., ±
.008
in. Th
is
hei
ght
is
det
ermined by che repla
cement
of
lami
co
id washers
be
c
wen
the
bottom
of
the
turntable
pivor (
24
or
3
6)
and
ch
e
hairpin
retainer on t
he
sha
ft
through
the pivot. Difficulties in
tape
tracki
ng
traced to im
pr
oper
rurntab
le
height
may be corrected by increasing
or
decreasing the n
umber
or thickness
of
these washers.
T
he
play
takeup
cluccl, assembly consists
of
a felt-lined
aluminum
disc
( 1
8)
,
and
a bakelite clutch ( 1
9)
which
is
spring-loaded
co
the
disc.
When
the
macl,i
ne
is
in
the
pl
ay
mode, che clutch
is
driven by rhe rub-
ber
belt
(69)
on
the
play rakeup pulley
(40).
Location of rhe felt-lined
al
umi
n
um
disc is
cr
itical
-a
clearance
of
.0
15
in. being required
be
-
tween
rhe
end
of
the
oi
lire
bear
i
ng
(21)
which
goes
through
rhe bake-
lice clutch ( 1
9),
and
the
bortom
of
the
aluminum
disc (
18).
This
clear-
ance, which can
not
be
measured directly
with
a
ga
uge because of
th
e
physical ar
rangement
can
be
sec
quire
accurately by the following in-
direa
m
ethod
:
Step
I:
in
sert
a removable .0 I5 in.
shim
or
feeler gauge
between
the
thrust
washer
that
rides on
the
i
nn
er
race of
the
lower ba
ll
bearing
(
22)
of
the
takeup
turntable
pivor (
24)
and
oilite
bush
ing
(
21).
Step 2: Assemble
the
conical
spring
(
20),
the
bakelite clutch ( l
9),
and
t
he
fe
lt
-l
ined
aluminum
disc (
18)
(in that
order)
on
rhe
tu
rnt
able
shaft
(
29).
Step 3:
Guide
rhe
end
of
the
oilice bushi
ng
through
the
hole in
the
center
of
the
bakeli
ce
clutch,
and
press
the
aluminum
disc
down
unti
l it borcoms firmly
on
th
e
end
of
the bushing.
Step
4:
H
olding
the
disc place in place,
tight
en the set screw in its
hub.
Step
5:
Remove
the
shim
or
gauge.
The
expansion
of
the
conical
spring
wi
ll
then
force
the
oilice
bushin
g back off
the
alumi-
num
disc, rhus creating
the
r
equi
red .015 in. clearance.
'
J
The
rubber-tired bakelite rewind
(31)
and
fast forward clutches
must
line
up
with
the
shock
relief
brake rollers (
5)
so
that
the
rollers
engage
the
full
width
of
the
tires.
ln
addition, rhe
rewind
clutch
(31)
should
be
aligned
for full-width conracc
with
the
rewind
idler (
7)
and
the
fast
forward clutch ( 16)
for
full
width
contact
with
the
motor
pulley (
61).
The
capstan speed
wi
ll
not
vary, since
the
capstan
is
driven
by
a
no
n-
slipping
nylon belt
and
synchronous motor. N o
adjustment
of
the
cap-
stan
speed will
be
necessary.
If
it is desired
co
check
the
capstan speed,
use a pre-recorded
5000
cycle tape, chat has been rec
orde
d
on
a
machine
of
known
accuracy,
and
an
eleccronic frequency
co
unter.
TABLE
4-1
Trouble
Tr
oubleshooti11g
PLAY Mode/ M,dfrmctions
Probable Cause
EXCESSIVE
OR
ERRATIC
HOLDBACK
TENS
I
ON
EXCESSIVE TAKE.UP
TENSION
DRIVE.MOTOR
OUT
OF
SYNCHRONISM
1.
Contaminated
rewind
clutch felt
(
30).
2.
Contaminated
rewind clutch
tire
(
31).
3. R
ewi
nd clutch s
pring
(32)
too
stiff.
Thi
s actually indicates
tam-
perin
g
or
carelessness in reasembly.
It
is
advisable
to
replace
the
spring
rather
than
ro
attempt
makeshift
readjuscment.
I.
Contaminated
play cakeup clut
ch
felt
(
18).
2.
Oilite
bearing
(
21)
bottoming
on
aluminum
clutch disc
(18).
Mini-
mum
clearance should
be
.OJ
5".
See s
ub
-
para
graph
8.4
below
for
adjustme
nt
procedure.
3.
Takeup
clutch
spring
(20)
too
stiff.
l.
Line
voltage
below 105 volts a-c.
2.
Excessive play rakeup tension. See
tro
uble above.
3.
Ny
lon
dr
i
ve
belt
(
68)
tension ex-
cessive. See
sub-paragraph
8.1 be-
lo
w.
4.
l3e
lt
tensioning
idler
(55)
drag-
gi
ng.
5.
Drivemoror
thrust
misadjusted. See
subparag
raph
8.2 below.
6.
Defeaive
drivemocor
starting
ca-
pacitor.
7.
Dry
bearings in drivemoror (
63),
capstan (
42),
or
capstan idler
(79).
See lubricat
ion
instruc
tions.
8. Defective
driv
emoro
r (
63).
Rew
i
nd
and
Fast
Fo
r
ward
Clutch Alignmen,t
Capstan Speed
4-9
www.SteamPoweredRadio.Com
4
-10
FLATTED OR
DENTED
CAPSTAN
IDLER
TIRE
DEFECTIVE
OR
JM
-
PROPEl?LY
INST
ALLflD
NYLON
DRIVE
BELT f6R)
Rfl\Y1
/ND
IDLER
17
I
NOT
DISENGAGING
FIW/\1
MOTOR PULLEY (61 I
REELS MISALIGN
ED
IViT
II
RESPECT
TO
TAPE
GUIDES
1.
If
the
capstan
idler
(
79)
is
left
en-
gaged
over
an
extended
period
when
the
machine
is
nm
operating,
the
idler
tire
may
become
dented.
If
running
the
machine
in
the
play
mode
for
several
hours
does
not
re-
store
the
tire
to
normal,
the
idler
must
be
replaced.
I.
Belt
spliced
improperly.
2.
Belt
installed
with
sp
lice
joim
toward
pulley.
3.
Belt
worn
because
misaligned
mo
-
ror
pulley
(
61)
causes
the
belt
to
track
against
one
of
the
capstan
pulley
nang
es
(
42).
I.
Contaminated
rewind
idler
guide
(
8).
I.
This
will
usually
cause
rape
scrape
which
may
or
may
not
be
audib
le
but
will
generally
appear
as
nmcer
.
See
subparagraph
8.'1
below.
TABLE
4-2
Tr
o11b
leshooting
REW
I
ND
and FAST
FORWARD
Mode
Malf11nctio11s
Trouble
TAKE.UP
TENSION
LOW
EXCESSIVE HOLD-
B,'lCK
TENSION
BRAKE
SHOCK RELIEF
ROLLE/?.
r
21
NOT
!?£
-
LEASING FROM FAST
r-orrn
'I
AIW
CLUTC
/1
{16)
REW
I
ND
IDLER 17!
NOT
ENGAGING
MOTOI?.
PULLEY
/6/)
BI
ND
IN
REWIND
IDLER
BEARING
(PART
OF
7)
MALFUNCTI
ONING
TURNTABLF. PJVO'/S
(24 or
36)
P
robab
le
Cause
Clutch
leaf
spring
(
17
and
32)
too
weak,
usually
caused
by
tamper
i
ng.
R
e-
place.
Never
attempt
co
increase
re-
wind
rakeup
tension
ro
o!Tset
mher
problems.
1.
Contam
i
nated
holclback
wipes
(25
or
3
7).
2.
Bakelite
drum
(
23
or
35)
on
which
wipe
operates
h
as
been
roughened.
Evidence
of
bent
or
misassemb
l
ed
parts.
Check
exploded
view, Fig.
4-4.
Bind
in
idler
guide
(8)
caused
by
con-
tamination.
Bind
in
turntable
centering
decent
(77).
TABLE
4-3
Trottbleshooting Starting, Stopping, and Shuttling Malfunctions
Trouble
TAPE LOOP
THROWN
ON
STARTING
IN
PLAY
MODE
(LOW
PLAY
TAKEUP
TENSION)
TAPE
LOOP
THROWN
ON
STOPPING
OR
SHUTTLING
Probable
Cause
1. Play
takeup
belt
(
69)
contam-
inated.
2.
Nylon
drive
belt
(
68)
contami-
nated.
If
either
the
play
rakeup
belt
or
the
nylon
drive
belt
is
contami-
nated
with
oil,
an
overoiled
motor
or
capstan
is indicated.
Clean
all
affected
parts
thoroughly
with
car-
bon
tetrachloride.
3.
Slippage
between
play
rakeup
belt
(69)
and
cl
utch
(
19)
due
ei
ther
to
weak
play
tak
eu
p
arm
sp
ring
(
41
)
or
bind
in play
rakeup
pulley
bea
r
ing
(
part
of
40).
4.
Bind
in
turntab
le
shaft
bearings
(22
or
24)
due
ro
contam
i
nation.
Clean
and
lubricate
with
two
or
three
drops
of
medium
weight
oil.
5.
Play
rakeup
brake
release ( 14) in-
operative
due
to
bind,
weak
or
un-
attached
spring
(
11
)
causing
shock
relief
ro
ll
er
(2)
to
drag
on
fast
forward
clutch
tire
( 1
6).
I.
One
or
boch
brake
shock
relief
ac
-
tuators
(
2)
binding.
2.
One
or
both
brake
shock
relief
springs
(
12)
off.
End
loops
on
these
springs
must
be
fully closed
to
prevent
their
becoming
discon-
nected.
3.
Bind
in
rurnrable
centering
decent
(
77).
4-11
www.SteamPoweredRadio.Com
V.
Electronic Assembly
The
electronic assembly consists of a record cha
nn
el, a reproduce chan-
nel, a bias and erase osci
ll
aror, and a power supply, mounted on a single
chassis.
The
record c
hann
el
consists
of
a rwo-srage mi
cropho
ne preamplifier
Vl0l
and
Vl02A
and
a three-stage amplifier,
Vl02B,
Vl03A,
Vl03B
(F
ig.
5.3).
Whe
n dummy
plug
J107P is inserted
in
receptacle
JI
06S in the micro-
phone
pre
am
pl
ifi
er, the micr
opho
ne
input
marches a hi
gh
impedance
microphone. A plug-in transformer, available as accessory
equipment,
will
pr
ovi
de
the
proper
march for a low impedance microphone.
The
MI
CROPHONE
inp
ut J
I0IS
and LJNE
IN
P
UT
J102S have sep-
arate controls
RI
06
and R 125 respectively. B
oth
inputs can be
use<l
simultaneously. Mix
ing
takes place in the first srage
of
the record
am-
plifier,
VI
028.
Signals in the record channel are picked off the
RE
C-
ORD
CALIBRATION
potentiometer R114 at the
output
of this srage,
a
nd
can be switched
to
the
output
amplifier thr
ough
the
MONITOR
SELECTOR sw
it
ch
S102, for monitoring.
Record equali
za
tion, accomplished in the
grid
circuit
of
VI
03A,
and
the ca
th
ode
circuit of V I03B,
is
adjusted by
trimmer
C I07. Plate volt-
age is supplied to
the
last stage ot the record amplifier,
Vl038
011/y
when
switch S20l on
th
e rape tran
sport
is
m the REC position.
The
r
ep
roduce channel consists
of
a
LWO-stage
reproduce
ampl
i
fie
r,
Vl04,
Vl05
and a
cw
o-stage
output
amplifier
Vl06A
and
Vl068.
The
signal from the reproduce head appears
at
connector
Pl
0 IP.
Re-
produce equalization
is
provided by
Cl
16
and
R 130. Level
is
adjusted
by potentiomecer
Rl
37.
The
re
prod
uce signal is f
ed
to
che
output
amplifier through che
MONI-
TOR
SELEC
TOR
switch when it is
in
tape position.
The
output
ampl
i-
fier consists
of
one voltage
amp
lification srage V106A, and a cathode
follower output stage V 106B, which is transformer-coupled ro
OUT-
PUT
connector J104S. A v-u meter and resistor shunt chis connector.
The
bias and erase oscillaror
is
an
LC
push-pull osci
ll
aror
operating
at
approxima
tely 100 kc.
The
NO
ISE
BALANCE
potenciometer R 147
co
mm
on
co
both
gr
i
ds
of
the
osci
ll
ator
is
adjusce<l
to
elimin
ate
any
asymmetry
in
wave form. Lack of wave symmetry would introduce a
d-c
current
in
the record head, causing
pe
rm
anent
magn
et
ization and a
resultant discorred signal. Bias level is adjusted
by
trimmer
Cl
13.
The
oscillacor, dependent
on
place voltage, operates only when switch
S20
1
is in
the
REC
position.
GENERAL
RECORD
CHANNEL
REPRODUCE
CHANN
E
BIAS
AND
ERASE
OSCILLATOR
5-1
www.SteamPoweredRadio.Com
S-2
BIAS
AND
ERASE
OSCILLATOR
ELECTRONIC
ALIGNMENT
ALIGNMENT
AND
TEST
EQUIPMENT
REQUIREMENTS
Head
Demagnetization
Demagnetization
Pro
ce
dure
The
d-c
plate
supply consisrs
of
a full wave rectifier
Vl08,
and
a ca-
pacitor-input L-C filter. A 6.3 volt secondary winding
on
the
power
transformer furnishes a-c
power
to
all heaters. Potentiometer R
150
HUM
BAL
is adjusted for
minimum
hum.
Al
ignment
consists in making all necessary adjustments for
proper
electronic performance. A recorder
out
of
alignment
may
be
character-
ized by poor frequency response, high noise, low
ourput,
high
distortion,
or
a combination
of
these faults. All
Ampex
recorders are completely
aligned
at
the
factory,
and
no
adjustments should
be
necessary.
The
overa
ll
performance checks outlined in Section 3 will generally serve
to
determine
if r
ealignment
is
necessary
at
any time.
Alignment
can
be
accomplished
without
removing
the
electronic as-
sembly from
the
case. If desired
the
electronic assembly can
be
with-
drawn
by
removing
the
four
screws
on
the
front
panel. Srand
the
case
in a vertical position and pull
the
electronic assembly forward. The
interconnecting cables between
the
electronic assembly and
the
rape
transport
arc
sufficiently long for access
co
all adjustments while
the
units
are
connected.
The
following equipm
ent
is
required for
proper
ali
gnment
and
resting:
A.
Audio
Oscillat
or-
Hewlett-Packard Model
200C
or
equivalent.
B.
Vacmmt
T1tbe
Vol
tm
eter- Hewlert-Packard Model
400C
or
equivalent.
C.
Amp
ex
Ali
gnment
Tap,'-Caralog
No.
5563.
This
rape
is
re-
corded ar 7 ½ ips
IO
db
below normal
operating
level as
defined in Section 3.
The
tape contains voice
an
noun
cements
of
rhe following cone sequence: reproduce head alignm
ent
tone, reference tone for reproduce level adjustment, cone
series for reproduce response check.
D.
Ampex
Head Demagnetize·r--Catalog No. 704.
E.
High
Impedance Headphones
F.
Small Screwdriver
Demagnetize rhc record and reproduce heads before
aligning
the
ma
-
chine.
The
erase head
req11ires
no
demag
netization. Magnetized heads
will generally produce
an
increase
of
5
co
10
db
in
noise level, distortion
of
the
recorded signal,
and
wi
ll
gradua
ll
y erase
the
high
frequencies
on
any
tap
e passed
over
them.
Step I:
Step
2:
Step 3:
Step 4:
Remove
both
rhe head cover
and
the
mu metal
sh
ield
over
rhe
head assembly.
Place
th
e
ON-OFF
switch in rhe
OFF
position.
Cover
the
t
ip
s
of
the
demagnerizer
with
scotch rape or mask-
ing
tape.
This
prevenrs scratching
the
heads.
Plug
the
demag-
nerizer inco a source of
11
7-volr a-c power.
The
head sequence fr
om
lefr
co
ri
ght
when
facing
the
machine,
is
erase head, record head, reproduce head.
Bring
the rips
of
rhe demagnerizer inro contact
with
rhe record
heaJ
stack.
The
tips
should straddle rhe
gap
in
the
cenrer
of
rhe stack.
Run
rhe rips slowly
up
and clown rhe srack several rimes, and rhcn
withdraw
rhe demagnerizer very slowly. Slow withdrawal
is
required
for thorough clemagnerizarion.
Step 5: R
epeat
step
4
on
the
reproduce head.
lr
is
not
necessary
to
demagnetize rhe erase head.
Step 6: Replace rhe head shield,
but
do
nor replace
the
head cover if
alignment
will follow.
The
foll
ow
ing sreps consritute rhe complete
alignment
of rhc reproduce
channel.
A. Reproduce
Head
Azimuth
Adjustmenr
B.
Reprodu
ce Level
Setting
C.
Reproduce Response Check
D.
Reproduce
Equalization
E.
Hum
Balance
Adjustment
Step
I:
Thread
the
alignment
rape
on
the
machine.
Terminat
e the
OUTPUT
conneetor with a 600
ohm
resisror and connect
the
vrvm across
this
load.
Plug
a
sec
of hi
gh
im
pedance head
phones
inro
the
phones jack
so
thar voice announcements
on
rhe tape
can
be
heard. If
nor
already done, remove
the
head
assembly cover,
but
nor rhe mu meral shield beneath it. Place
the
MONITOR
SELECTOR switch in
TAPE
position, and
start
the
machine
in
rhe reproduce mode.
The
head
alignment
cone will
be
announced first.
Step 2: Inse
rt
a small screw
driv
er
thro
ugh
rhe access hole nearesr rhe
right hand edge
of
the
head shield, and adjust
the
azimuth
screw for
maximum
output
observed
on
the
vtvm.
If
the
head
is far out of alig
nm
ent, several
minor
peaks occurri1tg on
eithe-r side
of
a
maximum
may
be
obJcrved.
Make
cerrain char
the
maximum
is
clearly 15
co
20
db
greater
than any
of
these
minor
peaks.
The
next
tone
on
rhe tape is for reproduce level setting.
Adjust
the
REPRODUCE
LEVEL (P.B. LEVEL)
pote
nt
iometer
Rl37
for a vcvm
reading
10
db
below normal operating level, which
is
approximate
ly
0.4 voles rms.
The
ne
xt
series
of
cones is for
the
reproduce r
es
ponse check.
Ob
serve
rhe response indicated
on
the
vrvm, and check
it
against specifications.
If
reproduce response fails
co
meet specifications,
the
troub
le
may
be
a
worn
or
otherwise faulty reproduce head, a partially erased
alignment
tape,
due
to
head magnetization,
or
improper
equalizarion
of
the re-
produce amplifier. Equalizarion can be checked and adjusred as indicated
below.
Demagnetization
Procedure
Reproduce
Channel
Alignment
Reproduce
Head
Azimuth Adjustment
Reproduce
level
Setting
Reproduce
Response Check
5-3
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